How Mosquitoes Bite: Get smart quick

Summer has arrived in Birmingham, and with it comes mosquito season. Given our research on Zika, and other mosquito-borne diseases, we would like to share some facts about how mosquitoes bite as part of our “Get Smart Quick” content series.

So, in 400 words, how do mosquitoes actually bite?

First, only female mosquitoes bite. They require the nutrients found in blood to produce eggs. Male mosquitoes feed mostly on flower nectar.

When feeding, the mosquito uses her proboscis — the long needle-like feature on her snout — to identify and extract blood from its target. However, this process is slightly more involved than most people think.

The proboscis (pro-boss-sis) is made up of six needles hidden under a protective sheath called a labium. When she bites, the labium folds backwards, exposing the six needles that make up her proboscis. These include:

A pair of maxillae, which have tiny saw-like teeth at their tips, used to pierce and cut the skin.

A pair of mandibles, inserted alongside the maxillae, used to spread the skin. The mandibles also provide leverage for digging the other needles deeper into the skin.

The Hypopharynx is a hollow needle used to secrete a saliva-like chemical that prevents blood from clotting. This saliva also causes the itchy reaction people experience, and serves as the fluid through which a female mosquito can transfer disease.

The labrum, the largest of the six needles, is a flexible straw-like feature used to explore for blood. Receptors at the tip of the labrum can detect naturally-occurring chemicals found in blood vessels, and guide the needle to its source. Like a modern oil or gas drill, the labrum can maneuver at sharp angles and explore horizontally underneath the skin surface (Check out this video captured by researchers at the Institut Pasteur in Paris). Once a vein is found, she uses the labrum to suck the blood.

While feeding, a mosquito will separate water from the blood and squeeze the water out of her rear end. This allows her to retain the greatest possible amount of nutrient-rich blood in each feeding.

The A. aegypti and A. albopictus will produce between 100-200 eggs per batch, and may lay approximately three batches in their 8-10 day lifecycle.

Eggs are often laid in, or near, standing water. However, A. aegypti eggs can survive in dry climates for periods longer than a year before hatching. Under these conditions, they hatch immediately after being submerged in any amount of water. Thus, the A. aegypti mosquito population is very difficult to control.